1. Field of the Invention
The present invention relates to a storage device and a storage device data life cycle control method.
2. Description of the Related Art
In storage devices, for example, storage regions based on an RAID (redundant array of independent disks) are constructed using storage devices such as hard disk drives, semiconductor memory drives or the like. For example, such physical storage regions (logical volumes) are provided to host computers (hereafter referred to as “hosts”) such as server machines or the like. Application programs operating in the hosts provide information processing services to client terminals connected to the hosts by writing data into the logical volumes or reading out data from the logical volumes.
The quantities of data that must be stored by storage systems are continually increasing; furthermore, depending on the type of data, there are also cases in which long-term storage is required. Accordingly, in order to meet this increasing demand, replacement with large-capacity disk drives, or the introduction of new type high-performance storage devices, has been seen.
Furthermore, a technique which is devised so that virtual volumes can be constructed by virtualizing logical volumes respectively possessed by respective storage devices, and these virtual volumes can be provided to respective hosts, is also known (Japanese Patent Application Laid-Open No. 2002-91706).
In conventional storage systems, new types of disk drives and new types of storage devices are introduced as necessary in order to increase the storage capacity and improve the response characteristics. However, the utilization value (utilization frequency) of data is not fixed, but drops as time passes according to the type of application program and the like. For example, in the case of a data base, data groups that constitute a monthly tabulation for a certain month are frequently utilized only during the period for which the monthly tabulation is created; after this monthly tabulation is completed, these data groups are hardly used at all until the deadline for the creation of a yearly tabulation arrives, and are merely stored “as is”. Furthermore, for example, in the case of email serving program, reference is made to email data only within a relatively short period following the receipt of this email; after a reply to the email is completed, the data is stored for a long period of time without being used.
Accordingly, even in cases where a high-speed volume constructed by a disk drive with good response characteristics is introduced, this high-speed volume becomes filled with data groups whose utilization rate has dropped as operation is continued. Meanwhile, in cases where data stored in a low-speed volume is referred to or updated, time is required for the reading and writing of such data, so that the response characteristics drop.
In cases where all of the volumes are constructed by high-speed volumes, the cost is increased; accordingly, it is necessary to operate using a mixture of high-speed volumes and low-speed volumes. However, as was described above, since high-speed volumes also eventually become filled with unnecessary non-urgent data, the high-speed characteristics cannot be utilized over a long period of time.
Meanwhile, a technique called data migration is also known. In the case of this data migration, for example, unnecessary non-urgent data is moved from the main volume to another volume, so that the empty capacity of the main volume is maintained. In this case, for example, since the question of which data corresponds to which file, the question of which files have a low frequency of use and the like cannot be grasped on the side of the storage device, data migration is performed on the basis of instructions from the side of the host.
Accordingly, it is necessary to grasp the frequency of use of the respective files on the side of the host, and to move these files from the current volume to another volume, so that the operating burden on the host side is increased, and the convenience of the system is poor. For example, the user must specify the file that is the object of movement, and must give instructions for the movement of this data. Furthermore, for example, the host must read out the file that is the object of movement from the current volume, and write this read-out file into another volume, so that the burden of data input-output on the network is increased.